Burger King is running a clever promotion in order to get people to use its mobile app. You can buy a Whopper for only one cent using the app if the Burger King you are buying it from is within 600 feet of a McDonald’s, reports CNBC. The app uses geofencing to determine the user’s location to a McDonald’s, and if they are within 600 feet, the deal will be enabled. Once they order the one-penny Whopper in the app, the app will give them directions to the nearby Burger King where they can pick their order up.

Burger King’s app can be downloaded for Android or iOS here. The one-cent Whopper promotion runs from now until Wednesday, December 12th.